FIG. 1.

Structure of poliovirus genomic RNA. (A) The single-stranded RNA is covalently linked to VPg at the 5′ end. The 5′NTR consists of two functional domains, the cloverleaf, and IRES elements. The open box depicts the polyprotein with coding regions for different viral proteins. Regions corresponding to structural and nonstructural domains are also indicated. The 3′NTR contains an heteropolymeric region and is polyadenylylated. (B) General features of poliovirus protein 2C with suggested functions as indicated by brackets and amino acid positions. A, B, and C refer to motifs conserved among superfamily 3 helicases and are required for the ATPase activity (adapted from Pfister and Wimmer [30]). Numbers in parentheses indicate amino acid locations within 2C. Poliovirus type 1 cre(2C) is located in the coding region corresponding to amino acids 109 to 127 (16). (C) Nucleotide sequence of PV-cre(2C) and the deduced amino acid sequence. (D) Predicted secondary structure of the PV-cre(2C) nt 4445 to 4504 in 2C and the mutants which were used in this study. Dots indicate the location of nucleotides which are different between type 1 and type 3 PV-cre(2C) (see Fig. 2).